Patent GB-853862-A (GB)
Title: Improvements relating to automatic telephone systems
Inventor: WARMAN BLOOMFIELD JAMES
IPC: H04M15/08
Filed: 1956-06-14
Abstract: 853,862. Automatic-exchange systems. SIEMENS EDISON SWAN Ltd. June 6, 1957 [June 14, 1956], No. 18426/56. Class 40 (4). In an arrangement for identifying a calling line, impulses resulting from the engagement of a wiper or wipers of a line-finder with associated bank contacts are fed to an impulsecounting device. As shown, in a system using high-speed motor-driven uniselectors, a group of line circuits divided into two sub-groups of a hundred each, of which Fig. 1 shows one from each sub-group, are accessible by a group of line-finders such as that shown in Figs. 3A, 3B and 3C, having two sets of wipers and a wiper-switching relay WS. Each sub-group of line circuits is associated with a start circuit, two such start circuits being shown in Fig. 2, while Figs. 4A and 4B show one of a group of registering-and-controlling circuits available in common to several groups of line-finders serving different groups of lines. The input terminals of an information-recording circuit are shown in Figs. 5A and 5B. A calling loop on line wires 1A, 2A of a line in sub-group " A " lowers the potential of the P-wire 3A and hence of the sub-group start wire 10A so that current flows in the collector circuit of transistor TA to operate start relay SA. This brings up relay STA in a free registering-and-controlling circuit, which connects test relays TS and TF to wipers CW7 and CW2 respectively and energizes latch magnet LM so that coupling-switch wipers CW1-CW8 rotate. Relay SA marks line finders of the relevant group by negative battery in contact bank CW7, while free line-finders are marked by negative battery in bank CW2. When coupling-switch CW reaches the first free linefinder in the relevant group, the operation of both relays TS and TF de-energizes latch magnet LM to stop the switch, simultaneously bringing up relays BH (Fig. 4A), SRA (Fig. 2), and RL (Fig. 3B), which busies the line-finder to wiper CW2. SRA disconnects start relay SA, and BH brings up relay BW and cooperates with RL to energize the line-finder wiper-switching relay WS since relay STA is operated. Relay BW prepares the impulsecounter, which comprises two ten-cathode scaling tubes D1 (units) and D2 (tens), connects wiper CW4 to wire 13, and completes over wiper CW3 an operating circuit for the line-finder latch magnet LMF, which sets the line-finder rotating and in operating its contact lmf 1 completes a connection between wire 13 and line-finder control wiper FW7 which encounters positive and negative battery respectively on alternate bank contacts. Wire 13 is the input to an impulse converter circuit which thus feeds one impulse to the counter for each position reached by the line-finder in its movement from normal. Off-normal contacts ONF2 operate the guard relay RR. Transistor T3 (Fig. 4B) tests the P-wires over wipers CW5 and FW6. The P-wire 3A of the calling line is at a sufficiently negative potential to cause current to flow in the collector circuit of transistor T3, firing tube CC1 and bringing up relay LF. This stops the line-finder by deenergizing the latch magnet LMF, operates relay LT, and applies a " record now " signal voltage V3 to the recording circuit, which proceeds to record the information presented by the signals on its input terminals. The line-finder (and hence the group of lines) is identified by a marking voltage V2 on the corresponding one of terminals MF, the subgroup of a hundred lines by a marking voltage V1 on one or other of terminals MA, MB (MA in the present case), and the particular line in the sub-group by markings from scaling tubes D1 and D2 on units terminals MU and tens terminals MT. The operation of relay LT connects wiper CW3 and hence the calling line to a circuit (not shown) for receiving dial impulses, applies busying earth to the P-wire of the calling line over wipers CW5 and FW6, and releases relays STA and (slowly) BW. The counter then returns to normal and the markings are removed from the input terminals of the recording circuit, the call proceeding in the usual way. A call from sub-group " B " is dealt with similarly, except that relays SB, STB and SRB operate instead of SA, STA and SRA, and the wiper-switching relay WS is not operated.